On Sunday morning, it was a tropical storm. By Monday morning, it had Category 5 winds. Super Typhoon Hagibis, currently moving near the Federated States of Micronesia in the northwestern Pacific Ocean, is a monster that gathered strength at one of the fastest rates ever observed on Earth.

The storm has a massive shield of towering thunderstorms surrounding a pinhole-like eye that is just a few miles across.

Its 160 mph winds firmly establish it as a Category 5-equivalent super typhoon, looming as a behemoth on satellite after a period of extremely rapid intensification.

“This is the most intensification by a tropical cyclone in the western North Pacific in 18 hours since Yates in 1996,” tweeted Philip Klotzbach, a hurricane researcher at Colorado State University. Maximum sustained winds increased at least 90 mph in 18 hours, nearly three and a half times the rate a storm would need to strengthen to constitute “rapid intensification,” based on the meteorological definition of that term.

During the peak of its extreme strengthening, Hagibis went from a tropical storm to a major hurricane-equivalent typhoon in six hours.

Super Typhoon Hagibis intensified at a rate comparable to that of Hurricane Patricia in 2015, whose winds strengthened by 120 mph in the eastern Pacific within 24 hours. That puts Hagibis in extraordinary company, considering that Hurricane Patricia was the most intense tropical cyclone ever observed in the Western Hemisphere and the second-strongest tropical cyclone on record worldwide.

The impacts

With gusts approaching 195 mph, Super Typhoon Hagibis is an absolute beast. It’s centered about 70 miles north of Saipan and is moving west-northwest at about 18 mph away from the island chain.

The worst conditions are ongoing, soon to subside during Monday afternoon Eastern Time. Typhoon warnings were up for Tinian, Saipan, Alamagan and Pagan islands. Fortunately, the eyewall passed well to the north of the islands, though “destructive” wind gusts of 74 mph or more were possible within the spiral rain bands.

The eyewall and eye did make a direct hit on Anatahan, a 13-square-mile uninhabited volcanic island, around noon Eastern Time on Monday.

A flash flood warning was up for Guam, as well, where total rainfall amounts of 3 to 7 inches were expected.

“At Saipan, their automated observing system is likely down right now because of the storm,” said Mike Middlebrooke, a senior forecaster at the National Weather Service in Guam. “It’s a heavily populated island. They probably got, and are still receiving, some low-end typhoon-force gusts.”

Saipan and Tinian were devastated by Category 5 equivalent Super Typhoon Yutu last year, which razed much of the island with 180 mph winds and a voracious storm surge. The storm hit two weeks after Hurricane Michael struck Florida’s Big Bend last October. President Trump declared an emergency for the Northern Mariana Islands on Oct. 24, 2018.

“They’re still recovering [from Yutu],” said Middlebrooke, referencing residents of Saipan and Tinian. “There are a lot of people still in makeshift housing since last October.”

Storm may target Japan

After pulling away from Micronesia, Hagibis is forecast to additionally strengthen, peaking with sustained winds of 170 mph over the open ocean late Monday night into Tuesday. From there, a gradual weakening trend will commence.

Hagibis is anticipated to make a gentle turn to the north, recurving far to the east of Taiwan. That puts Japan squarely in its sights this weekend.

While a lot can change six days out, odds favor Hagibis making landfall somewhere along the main island of Japan sometime Saturday into Sunday. However, exactly where remains to be seen, as does its intensity at that point. It is too early to speculate on specific impacts to Tokyo, though the potential exists for a Category 1 or 2-equivalent typhoon to pass close to Japan’s most populous corridor.

Irrespective of where Hagibis ultimately ends up, the storm has the potential to influence U.S. weather in about 10 days’ time.

Once Hagibis undergoes mid-latitude transition over the Bering Sea, it will add a bit of a “turbo boost” to the Pacific jet stream. That pulse of mid-level energy will arrive over the Pacific Northwest sometime between Oct. 16 and Oct. 18, possibly bringing a period of active weather.

North of there, a period of storminess may be in the offing from the Gulf of Alaska down to the western shores of British Columbia. The perturbation to the jet stream may also enhance ridging, or a northward shunting of the jet stream, in the West, favoring a spell of above-normal temperatures for that region. The exact long-term implications of the storm remain to be seen.

Rapidly intensifying storms are a potential climate signal

Rapidly intensifying storms like Super Typhoon Hagibis are becoming more common in the North Atlantic Ocean Basin, and are expected to become more frequent around the world as global warming in response to human activities continues.

Kerry Emanuel, a hurricane researcher and atmospheric scientist at MIT, wrote a 2017 paper in which he studied modeled Atlantic storms. He found an uptick in the number of storms that would rapidly intensify just before landfall. Even more alarming was Emanuel’s simulation that storms intensifying by 70 mph or more within 24 hours — which he found had occurred on the average of only once per century in the late 20th-century climate — may occur “every 5-10 years by the end of this century.”

Another study, published last year, found that with continued global warming, more tropical cyclones will undergo rapid intensification than had done so before. It also found, using a climate model capable of simulating these massive storms amid changing atmospheric and oceanic conditions, that future storms could be so intense that a new category — Category 6, might be required to describe their intensity.

For the period between 2016 and 2035, the study found that there would be an 11 percent uptick in major tropical cyclones, of Category 3 intensity or greater, for example.

It also found 72 storms with maximum sustained winds above 190 mph by the end of the century, compared with nine such storms in a simulation of the late-20th-century climate.